A balloon-borne experiment has turned up a mysterious radio signal that seems to be coming from beyond the Milky Way. Astronomers do not yet have a clear explanation for the static but say it could come from the universe s first generation of stars. The noise was found with a balloon-borne instrument called ARCADE which flew for four hours at an altitude of 37 kilometres above Texas in July 2006. The instrument mapped a doughnut-shaped region that covered some 7 of the sky. The team intended to look for slight deviations in the spectrum of the cosmic microwave background the first radiation emitted after the big bang. Instead after subtracting known radio sources in the Milky Way and other galaxies an unexplained radio static was left that seemed to pervade the sky and was some six times louder than all known astronomical sources combined at the same radio frequency. “It is exciting evidence of something new and interesting going on in the universe ” ARCADE leader Alan Kogut of the Goddard Space Flight Center in Greenbelt Maryland said on Wednesday at a meeting of the American Astronomical Society in Long Beach California.